The invention relates to a gear unit for gate drives, preferably for driving sectional and roller gates.
The use of such gear units for operating industrial gates is known. Frequently used industrial gates are sectional and roller gates. An important part of the sectional gates is a gate shaft preferably in the form of a torsion spring shaft, which is connected to the gate by means of ropes and rope drums. The gate shaft is accommodated in a hollow shaft of a geared motor in such a way that in the turning direction of the hollow shaft, a form-locking connection is produced. With roller gates, such a gate shaft not only serves to operate the roller gate, but must also hold the wound up roller gate. To obtain, in the turning direction, form-locking connection between the gate shaft and the hollow shaft accommodating the same, the gate shafts are provided, for example, with grooves to hold a fitting spring or with multiple side surfaces; a corresponding negative profiling is provided on the inside of the hollow shaft. Corresponding to the great variation in fitting spring widths and types and differently shaped multiple side surfaces as well as other surface profiles, a multitude of differently constructed hollow shafts must be made available. The hollow shaft together with a mechanical transmission gear, as well as an electric drive motor, generally forms part of a structural unit. Accordingly, due to the profiling of the gate shaft, many different types of gear motors must be manufactured, which considerably increases costs.
It is the object of the present invention to create a gear unit for gate drives, with which different shapes of shafts, in particular gate shafts, can be driven.
According to the invention, this object is achieved in that the gear unit comprises a hollow shaped part which can be introduced into the hollow shaft; the outside and inside of the hollow shaped part are made in such a way that the connection with a shaft accommodated within the hollow shaped part as well as connection with the hollow shaft accommodating the hollow shaped part, are both form-locking in the turning direction. An advantage of this arrangement is that, when the shaft being accommadated within the hollow part is replaced by a shaft of a different size and/or shape, only the hollow part need be replaced with hollow part having a corresponding profiling on the inside and which can be inserted into the outer hollow shaft. It, therefore, is not necessary to replace the entire geared motor. Because the outside of the hollow shaped parts is shaped, in such a way that in the turning direction, a form-locking connection exists with the outer hollow shaft, only a few different types of geared motors need to be manufactured; adaptation to the specific shapes of the gate shafts always takes place by the insertable hollow shaped parts.
In a preferred embodiment of the present invention, the hollow shaped part is provided on the outside with toothing, a multiple-groove profile or (FIG. 6) or a polygon profile (FIG. 5), as a result of which in the turning direction, a form-locking connection with corresponding inside toothing or with a corresponding profile on the inside of the outer hollow shaft can be produced. A force-locking connection between the hollow shaped part and the outer hollow shaft in the direction of the joint is not necessary, as there are no axial forces; contact between the two parts, to a large extent, prevents shifting of the hollow shaped part.
The connection between the hollow shaped part and hollow shaft may be made form-locking in the turning direction by means of a fitting spring and/or a wedge (FIG. 7). This embodiment has the advantage that the manufacture of the hollow shaft as well as of the hollow shaped part can be carried out relatively simply because of the absence of toothing or a profile and with the same: effect. The connection between the hollow shaped part and hollow shaft by a fitting spring or wedge or by a multiple side toothing or a profile, with the same effect, is preferably made detachable to permit easy exchanging of the hollow shaped part.
In a further embodiment of the invention in the turning direction form-locking Connection between the hollow shaped part and the interior shaft accommodated in the same, preferably a gate shaft, takes place by a fitting spring or a wedge (FIG. 8) or by a profiling of the shaft and a corresponding negative profiling of the inside of the hollow shaped part (ref. no. 28 in FIGS. 1-3). Such a connection is also preferably made detachable to permit an easier separating of the shaft from the hollow shaped part. The connection between the shaft and the hollow shaped part is preferably not made force-locking in the direction of the joint, since an axial shifting of the shaft is prevented by the geared motors or hollow shaped parts delimiting the shaft ends in the axial direction.
The hollow shaped part may, on one side, be closed off by a wall, as a result of which the hollow shaft of the gear unit can be protected against contact with the shaft which it accommodates and accordingly against wear.
According to a preferred embodiment of the present invention, the hollow shaft and/or the hollow shaped part are made of drawn or extruded material.
The drawn or extruded material may comprise steel and/or aluminium.
For the form-locking engaging of the hollow shaft in a profiled drive element of the gear unit, preferably in the form of a worm wheel, the outside of the hollow shaft may be provided with toothing.